As I cradle my glass-backed iPhone—consciously aware of how fragile these things are when dropped—Darren Wilson casually tells me how his phone "just literally fell 20 feet."

Of course, I want to be sure that I didn't misunderstand. He actually meant a paltry height of two feet instead, right? But Wilson confirms what I had feared: Twenty feet. Like it was no big deal. I clutch my iPhone just a little bit more tightly.

Wilson works as a pipe fitter for Siemens, in the Canadian arm of the German technology conglomerate. His phone is a Motorola ES400, an old Windows mobile handset, and it isn't exactly what you'd call slim. With the standard battery, it measures 0.67 inches. It increases to a chunky 0.85 inches with an extended cell.

The ES400 is a rugged phone, built to withstand everything from dust to drops and accidental submersion. It's the sort of device that can be used outdoors for extended periods of time, and can be pushed well past the operating limits of most other phones.

Not that Mr. Wilson has a choice of other phones, of course. Siemens has custom software for processing work orders and invoices, keeping track of inventory and submitting timesheets. It all runs on Microsoft’s legacy Windows Mobile system. Worse still, the aging OS hasn’t seen any significant updates since 2010. In technology years, that's practically a lifetime.

But outside of the enterprise—in smaller companies and firms where legacy platforms and software are more rare—it's a different story. Concrete contractors, construction workers and field technicians are apparently trading their traditional rugged phones for regular consumer devices. In the place of an ES400, imagine an iPhone 4S, enclosed in a ruggedized case.

Microsoft may be all about Windows Phone 7 these days, but many customers still rely on its legacy Windows Mobile OS.

Motorola

From a technical standpoint, given the choice, it's easy to understand why someone would pick an iPhone 4S over an old Windows device. Rick Yelton, editor at large with construction media company Hanley Wood, told me that, as far as features are concerned, it's hard for traditional manufacturers in the rugged phone industry to compete.

"Why aren't they in vogue? Because they don't change the technology fast enough," Mr. Yelton said.

But there are tradeoffs to be had as smaller business opt for more modern devices too—and being rugged still means more than having a good case.

Rugged rankings

While it's easy to claim that a device is ruggedized, there are actually industry specifications to prove it. One is an Ingress Protection rating (IP). This is a measure of a device's ability to repel varying degrees of dust and/or water from entering a device.

Mr. Wilson's ES400, for example, meets IP42 sealing requirements. The first number—the device's foreign body ranking, on a scale of 0 to 6—indicates its ability to prevent dust, particles, or other objects from entering the enclosure. In this case, a rank of four means the device is protected against granular particles down to 1mm in size. It's not until a device is given a ranking of five that it is considered dust protected, with six indicating a device is dust-proof.

The second number—a device's water protection ranking—has a slightly larger scale, from zero to eight. A device is not considered safe from immersion until it achieves a ranking of seven, and even then, only for a temporary period of time at limited depths. The highest ranking of eight indicates more permanent immersion, often while under pressure—though this too can differ from device to device. A two, however, as found on the ES400, only indicates the ability to resist light rainfall or sprays.

Some manufacturers will also subject their devices to US Military Standard 810G specifications for drop and impact-resistance. For example, Sonim rates its current line of rugged phones as capable of withstanding 6.5 feet drops onto bare concrete, though this can vary amongst manufacturers.

The Defender

Talk to anyone in the field with a rugged phone case, and they'll usually reference the Defender. This is Otterbox's flagship protection line for iPhones, BlackBerrys and myriad other devices, and for good reason. The company likes to demonstrate the Defender at events by casually throwing it on the floor, and touts the product as offering "total protection for the construction industry."

The problem—if you can call it that—is that the Defender series doesn't do anything to improve a device's IP or Military Standard specifications. In other words, "you really have to design the PDA from the bottom up to attain this properly," says Liverpool-based Rugged and Mobile, a hardware services company for rugged devices. Instead, they refer to a case's ability to increase the durability of a phone, as opposed to its ruggedness.

The Otterbox website does mention that its Defender line "provides added protection against bump, shock, drop, and dust intrusion," though it's unclear how this additional protection is measured. Nowhere on the site is there mention of IP or Military Specification tests, and the company has yet to respond with clarification regarding its testing procedures as of this article.

But even if the Otterbox isn't rugged in the traditional sense, people in the industry are still eager to see how it compares. Brandon Wright, for example, works at a company called Data Drill, which provides communication equipment—including rugged Motorola and Samsung feature phones—to oil and gas companies operating in Alberta, Canada. He says his company recently sent out their first iPhone with one of his field techs, equipped with an Otterbox Defender case.

Shaun Hollinshead, a driver with North American transportation service Contrans Flatbed Group, also owns a Defender-clad iPhone. It replaced his similarly protected BlackBerry device. Both have survived falls unscathed.

However, Hollinshead isn't quite so sure it can compare to his old rugged phone, an push-to-talk (iDEN) handset on Canada's MiKE cellular network.

"I dropped that thing twice from 35 feet, no problem," he says. "It just hit the ground. The battery came out, you slammed it back together, and the thing worked."